As people enter secure areas, it is important that they be scanned to ensure that they are not entering with weapons or explosives. In addition to airport departure gates, office buildings, stadiums and other such venues must have fast, accurate, non-intrusive means of detecting threats concealed under a person's clothing.
Portal-based screening systems at security check points may use millimeter wave technology to image objects concealed beneath clothing on a human body. Specific characterization of weak dielectric threat objects, however, is a challenge for millimeter-wave scanning systems. Currently deployed focused mm-wave systems do not specifically address dielectric material. Dielectric slabs appear as anomalies on the body, but are uncharacterized. The inability to accurately characterize dielectric materials with millimeter-wave scanning systems may result in an unacceptable number of false alarms. A false alarm may lead to time-consuming investigative procedures such as pat-downs and other undesirable measures.